Darkness on the edge (and center) of town

Last weekend during Earth Hour, more than 1,000 cities in over 80 countries dimmed their lights starting at 8.30 p.m. local time to raise awareness about climate change and the threat from rising greenhouse gas emissions.

REUTERS/Yiorgos Karahalis

On the next page you’ll find a link from the Boston Globe’s The Big Picture to a series of before-and-after photographs which, (starting with the second one) will fade between “on” and “off” when clicked.